1,622 research outputs found

    Upregulation of PD-L1 expression in breast cancer cells through the formation of 3D multicellular cancer aggregates under different chemical and mechanical conditions

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    © 2019 Elsevier B.V. Expression of programmed death-ligand 1 (PD-L1) in cancer cells plays an important role in cancer-immune cell interaction. The emerging evidence suggests regulation of PD-L1 expression by several tumor microenvironmental cues. However, the association of PD-L1 expression with chemical and mechanical features of the tumor microenvironment, specifically epidermal growth factor receptor (EGFR) signaling and matrix stiffness, remains elusive. Herein, we determine whether EGFR targeting and substrate stiffness affect the regulation of PD-L1 expression. Breast carcinoma cell lines, MCF7 and MDA-MB-231, were cultured under different conditions targeting EGFR and exposing cells to distinct substrate stiffness to evaluate PD-L1 expression. Furthermore, the ability to form aggregates in short-term culture of breast carcinoma cells and its effect on expression level of PD-L1 was probed. Our results indicated that PD-L1 expression was altered in response to both EGFR inhibition and substrate stiffness. Additionally, a positive association between the formation of multicellular aggregates and PD-L1 expression was observed. MDA-MB-231 cells expressed the highest PD-L1 level on a stiff substrate, while inhibition of EGFR reduced expression of PD-L1. The results suggested that both physical and chemical features of tumor microenvironment regulate PD-L1 expression through alteration of tumor aggregate formation potential. In line with these results, the in-silico study highlighted a positive correlation between PD-L1 expression, EGFR signaling, epithelial to mesenchymal transition related transcription factors (EMT-TFs) and stemness markers in metastatic breast cancer. These findings improve our understanding of regulation of PD-L1 expression by tumor microenvironment leading to evasion of tumor cells from the immune system

    Machine learning reveals mesenchymal breast carcinoma cell adaptation in response to matrix stiffness.

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    Epithelial-mesenchymal transition (EMT) and its reverse process, mesenchymal-epithelial transition (MET), are believed to play key roles in facilitating the metastatic cascade. Metastatic lesions often exhibit a similar epithelial-like state to that of the primary tumour, in particular, by forming carcinoma cell clusters via E-cadherin-mediated junctional complexes. However, the factors enabling mesenchymal-like micrometastatic cells to resume growth and reacquire an epithelial phenotype in the target organ microenvironment remain elusive. In this study, we developed a workflow using image-based cell profiling and machine learning to examine morphological, contextual and molecular states of individual breast carcinoma cells (MDA-MB-231). MDA-MB-231 heterogeneous response to the host organ microenvironment was modelled by substrates with controllable stiffness varying from 0.2kPa (soft tissues) to 64kPa (bone tissues). We identified 3 distinct morphological cell types (morphs) varying from compact round-shaped to flattened irregular-shaped cells with lamellipodia, predominantly populating 2-kPa and >16kPa substrates, respectively. These observations were accompanied by significant changes in E-cadherin and vimentin expression. Furthermore, we demonstrate that the bone-mimicking substrate (64kPa) induced multicellular cluster formation accompanied by E-cadherin cell surface localisation. MDA-MB-231 cells responded to different substrate stiffness by morphological adaptation, changes in proliferation rate and cytoskeleton markers, and cluster formation on bone-mimicking substrate. Our results suggest that the stiffest microenvironment can induce MET

    Cardiac Explant-Derived Cells Are Regulated by Notch-Modulated Mesenchymal Transition

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    Progenitor cell therapy is emerging as a novel treatment for heart failure. However the molecular mechanisms regulating the generation of cardiac progenitor cells is not fully understood. We hypothesized that cardiac progenitor cells are generated from cardiac explant via a process similar to epithelial to mesenchymal transition (EMT).Explant-derived cells were generated from partially digested atrial tissue. After 21 days in culture, c-Kit+ cells were isolated from cell outgrowth. The majority of explant-originated c-Kit+ cells expressed the epicardial marker Wt1. Cardiac cell outgrowth exhibits a temporal up-regulation of EMT-markers. Notch stimulation augmented, while Notch inhibition suppressed, mesenchymal transition in both c-Kit+ and c-Kit- cells. In c-Kit+ cells, Notch stimulation reduced, while Notch inhibition up-regulated pluripotency marker expressions such as Nanog and Sox2. Notch induction was associated with degradation of β-catenin in c-Kit- cells. In contrast, Notch inhibition resulted in β-catenin accumulation, acquisition of epitheloid morphology, and up-regulation of Wnt target genes in c-Kit- cells.Our study suggests that Notch-mediated reversible EMT process is a mechanism that regulates explant-derived c-Kit+ and c-Kit- cells

    The E-cadherin repressor Snail is associated with lower overall survival of ovarian cancer patients

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    Epithelial ovarian cancer is the leading cause of death among female genital malignancies. Reduced expression of the cell adhesion molecule E-cadherin was previously shown to be associated with adverse prognostic features. The role of the E-cadherin repressor Snail in ovarian cancer progression remains to be elucidated. We analysed formalin-fixed and paraffin-embedded specimens of 48 primary ovarian tumours and corresponding metastases for expression of E-cadherin and Snail by immunohistochemistry. We found a significant correlation between E-cadherin expression in primary cancers and their corresponding metastases (P<0.001). This correlation was found for Snail expression as well (P<0.001). There was a significant (P=0.008) association of reduced E-cadherin expression in primary ovarian cancer with shorter overall survival. Similarly, Snail expression in corresponding metastases (P=0.047) was associated with reduced overall survival of the patients. Additionally, the group of patients showing reduced E-cadherin and increased Snail immunoreactivity in primary tumours and corresponding metastases, respectively, had a significantly higher risk of death (P=0.002 and 0.022, respectively) when compared to the patient group with the reference expression profile E-cadherin positive and Snail negative. Taken together, the results of our study show that the E-cadherin repressor Snail is associated with lower overall survival of ovarian cancer patients

    Cancer stem-like cells from head and neck cancers are chemosensitized by the Wnt antagonist, sFRP4, by inducing apoptosis, decreasing stemness, drug resistance and epithelial to mesenchymal transition

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    Cancer stem cells (CSCs) of head and neck squamous cell carcinoma (HNSCC) are defined by high self-renewal and drug refractory potential. Involvement of Wnt/ß-catenin signaling has been implicated in rapidly cycling cells such as CSCs, and inhibition of the Wnt/ß-catenin pathway is a novel approach to target CSCs from HNSCC. In this study, we found that an antagonist of FrzB/Wnt, the secreted frizzled-related protein 4 (sFRP4), inhibited the growth of CSCs from two HNSCC cell lines, Hep2 and KB. We enriched the CD44+ CSC population, and grew them in spheroid cultures. sFRP4 decreased the proliferation and increased the sensitivity of spheroids to a commonly used drug in HNSCC, namely cisplatin. Self-renewal in sphere formation assays decreased upon sFRP4 treatment, and the effect was reverted by the addition of Wnt3a. sFRP4 treatment of spheroids also decreased ß-catenin, confirming its action through the Wnt/ß-catenin signaling pathway. Quantitative PCR demonstrated a clear decrease of the stemness markers CD44 and ALDH, and an increase in CD24 and drug-resistance markers ABCG2 and ABCC4. Furthermore, we found that after sFRP4 treatment, there was a reversal in the expression of epithelial to mesenchymal (EMT) markers with the restoration of the epithelial marker E-cadherin, and depletion of EMT-specific markers twist, snail and N-cadherin. This is the first report demonstrating that the naturally occurring Wnt inhibitor, sFRP4, can be a potential drug to destroy CSC-enriched spheroids from HNSCCs. The repression of EMT and the decrease in stemness profile further strengthen the use of sFRP4 as a potent therapeutic against CSC

    Dunning rat prostate adenocarcinomas and alternative splicing reporters: powerful tools to study epithelial plasticity in prostate tumors in vivo

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    Using alternative splicing reporters we have previously observed mesenchymal epithelial transitions in Dunning AT3 rat prostate tumors. We demonstrate here that the Dunning DT and AT3 cells, which express epithelial and mesenchymal markers, respectively, represent an excellent model to study epithelial transitions since these cells recapitulate gene expression profiles observed during human prostate cancer progression. In this manuscript we also present the development of two new tools to study the epithelial transitions by imaging alternative splicing decisions: a bichromatic fluorescence reporter to evaluate epithelial transitions in culture and in vivo, and a luciferase reporter to visualize the distribution of mesenchymal epithelial transitions in vivo

    Suppression of TGFβ-Induced Epithelial-Mesenchymal Transition Like Phenotype by a PIAS1 Regulated Sumoylation Pathway in NMuMG Epithelial Cells

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    Epithelial-mesenchymal-transition (EMT) is a fundamental cellular process that is critical for normal development and tumor metastasis. The transforming growth factor beta (TGFβ) is a potent inducer of EMT like effects, but the mechanisms that regulate TGFβ-induced EMT remain incompletely understood. Using the widely employed NMuMG mammary epithelial cells as a model to study TGFβ-induced EMT, we report that TGFβ downregulates the levels of the SUMO E3 ligase PIAS1 in cells undergoing EMT. Gain and loss of function analyses indicate that PIAS1 acts in a SUMO ligase dependent manner to suppress the ability of TGFβ to induce EMT in these cells. We also find that TGFβ inhibits sumoylation of the PIAS1 substrate SnoN, a transcriptional regulator that antagonizes TGFβ-induced EMT. Accordingly, loss of function mutations of SnoN sumoylation impair the ability of SnoN to inhibit TGFβ-induced EMT in NMuMG cells. Collectively, our findings suggest that PIAS1 is a novel negative regulator of EMT and reveal that inhibition of the PIAS1-SnoN sumoylation pathway represents a key mechanism by which TGFβ induces EMT, with important implications in normal development and tumor metastasis

    FGFR1-Induced Epithelial to Mesenchymal Transition through MAPK/PLCγ/COX-2-Mediated Mechanisms

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    Tumour invasion and metastasis is the most common cause of death from cancer. For epithelial cells to invade surrounding tissues and metastasise, an epithelial-mesenchymal transition (EMT) is required. We have demonstrated that FGFR1 expression is increased in bladder cancer and that activation of FGFR1 induces an EMT in urothelial carcinoma (UC) cell lines. Here, we created an in vitro FGFR1-inducible model of EMT, and used this model to identify regulators of urothelial EMT. FGFR1 activation promoted EMT over a period of 72 hours. Initially a rapid increase in actin stress fibres occurred, followed by an increase in cell size, altered morphology and increased migration and invasion. By using site-directed mutagenesis and small molecule inhibitors we demonstrated that combined activation of the mitogen activated protein kinase (MAPK) and phospholipase C gamma (PLCγ) pathways regulated this EMT. Actin stress fibre formation was regulated by PLCγ activation, and was also important for the increase in cell size, migration and altered morphology. MAPK activation regulated migration and E-cadherin expression, indicating that combined activation of PLCγand MAPK is required for a full EMT. We used expression microarrays to assess changes in gene expression downstream of these signalling cascades. COX-2 was transcriptionally upregulated by FGFR1 and caused increased intracellular prostaglandin E2 levels, which promoted migration. In conclusion, we have demonstrated that FGFR1 activation in UC cells lines promotes EMT via coordinated activation of multiple signalling pathways and by promoting activation of prostaglandin synthesis
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